1. Field of the Invention
The present invention relates to an optical disk reading device, and in particular, to a device for latching and forcibly releasing the lid of a portable compact disk player.
2. Description of the Prior Art
The latching and release device for the lids of conventional portable compact disk players is generally designed to have a release spring that pushes against the lid when it is in a latched position. When the lid is about to be popped open, the normal bias (which acts as a restoring force) of the compressed release spring can be used to overcome the holding force of the compact disk holding device, and together with the torque applied at the pivot axle, causes the lid to be released. However, the normal bias of the release spring constantly acts on the lid when the lid is in the latched position. In addition, in order to overcome the holding force of the holding device when the lid is released, the force of the normal bias must be, in general, quite large. If the lid is made of a plastic material, when the compact disk player is stored or used in a high-temperature environment, the lid may be subjected to heat such that the rigidity of the material is reduced. As a result, the force of the normal bias of the release spring can easily cause the lid to deform, which will affect the overall appearance of the compact disk player and may cause abnormal playback, among other disadvantages.
FIG. 1 illustrates a conventional compact disk player system, which comprises at least a lid seat (not shown in the figure), a lid 1a, a solenoid base 2a, a solenoid 3a, a catch 4a and a torsion spring 5a (which functions as the release spring), among other components. When the lid 1a covers the lid seat, the catch at the upper end of the catch 4a hooks into the latching hole 10a at the front edge of the lid 1a, while at the same time, the end of the torsion spring 5a pushes against the contact part at the front edge of the lid 1a to provide a normal bias that acts as a restoring force. When the lid 1a is to be opened up from its seat, an extension plunger 30a at the front end of the solenoid 3a retracts when the coil is energized. This causes the catch part of the catch 4a to rotate and withdraw from the latching hole 10a, which allows the normal bias (restoring force) of the torsion spring 5a to pop the lid 1a open.
In addition, as shown in FIG. 2(a), when the release spring is in an unstressed state (i.e., when no external force is applied), the free length of the release spring is l0. However, when the lid is in a latched state as shown in FIG. 2(b), the release spring is subjected to a predetermined compression force such that the length of the spring is l1 and the velocity of the lid is v1s=0, while a gap h remains between the lid and the spring. In the instant when the lid is about to be popped open as shown in FIG. 3(c), the lid has an initial velocity v2s, and l2=l1+h, and in this manner, an applied force is generated:F=impact force+restoring force,with the formula calculated as follows, where the mass of the spring is m and the spring constant is k:                (a) when the lid is in a latched state,        Kinetic energy T1=(½)*ms(v1s)2=0        Potential energy V1=(½)*k(l0−l1)2         (b) In the instant when the lid is about to be popped open        Kinetic energy T2=(½)*ms(v2s)2         Potential energy V2=(½)*k(l0−l1)2         (c) Using the law of conservation of energy T1+V1=T2*V2        
      v    2    s    =                              k          ⁡                      (                                          2                ⁢                                  l                  0                                            -                              2                ⁢                                  l                  1                                            +              h                        )                          ⁢        h                    m        3                            (4) Applied force F=impact force+restoring force        
                    =                ⁢                                            m              s                        ⁢                                          Δ                ⁢                                                                  ⁢                v                                            Δ                ⁢                                                                  ⁢                t                                              +                      k            ⁡                          (                                                l                  0                                -                                  l                  2                                            )                                                              =                ⁢                                            m              s                        ⁢                                          v                2                s                                            Δ                ⁢                                                                  ⁢                t                                              +                      k            ⁡                          (                                                l                  0                                -                                  l                  2                                            )                                          
Thus, there remains a need for a device for latching and forcibly releasing the lid of a portable compact disk player which overcomes the drawbacks described above.